Smoking cessation and lung cancer: never too late to quit
Authors: Rachael L Murray, Emma O’Dowd
Journal: The Lancet Public Health (2023)

Although smoking rates in high-income countries have decreased since 2000, smoking remains a key modifiable risk factor for premature mortality and is the number-one risk factor for lung cancer. Continued smoking is associated with a substantially increased risk of all-cause mortality and tumour recurrence in patients with a diagnosis of lung cancer;1Parsons A Daley A Begh R Aveyard P Influence of smoking cessation after diagnosis of early stage lung cancer on prognosis: systematic review of observational studies with meta-analysis.BMJ. 2010; 340b5569Crossref PubMed Scopus (560) Google Scholar previous studies have shown improved recurrence-free and overall survival in former smokers with lung cancer compared with current smokers. A 2022 meta-analysis by Caini and colleagues2Caini S Del Riccio M Vettori V et al.Quitting smoking at or around diagnosis improves the overall survival of lung cancer patients: a systematic review and meta-analysis.J Thorac Oncol. 2022; 17: 623-636Summary Full Text Full Text PDF PubMed Scopus (31) Google Scholar showed that quitting smoking at or around the time of lung-cancer diagnosis (ie, within 12 months) was associated with improved overall survival. The analysis by Aline F Faers and colleagues3Fares AF Li Y Jiang M et al.Association between duration of smoking abstinence before non-small-cell lung cancer diagnosis and survival: a retrospective, pooled analysis of cohort studies.Lancet Public Health. 2023; 8: e691-e700Google Scholar in this issue of The Lancet Public Health is the first to look at the effects of duration of smoking cessation before a diagnosis of lung cancer on overall and non-small cell lung cancer (NSCLC)-specific survival across four continents (ie, Asia, Europe, North America, and South America). It highlights the benefits of stopping smoking, even in the year before diagnosis, and shows increasing benefit with longer durations of abstinence (particularly for people who quit more than 5 years before diagnosis). Their findings add to the evidence that quitting smoking is beneficial at any time. However, because the greatest gains in NSCLC-specific survival come with a longer duration of quitting, all health-care professionals should be reinforcing the benefits of smoking cessation in all patient interactions and effective, evidence-based, stop-smoking interventions should be available for all people who smoke and are willing to stop. Early intervention will maximise the duration from the timepoint that an individual quits smoking to the timepoint of a potential lung-cancer diagnosis and therefore maximise the benefits. Faers and colleagues3Fares AF Li Y Jiang M et al.Association between duration of smoking abstinence before non-small-cell lung cancer diagnosis and survival: a retrospective, pooled analysis of cohort studies.Lancet Public Health. 2023; 8: e691-e700Google Scholar modelled the probability of being alive and the cumulative incidence of death from NSCLC at 5 years and at 10 years for a prototypical White, male patient with stage 1 lung adenocarcinoma who was younger than 65 years with less than 40 pack years of smoking history and being treated at the Mayo Clinic (Rochester, MI, USA). Their pooled data showed improved overall survival in ever smokers for women and people of Asian ethnicity. Such subgroup differences have been reported by other studies. For example, in the small subsample of women included in the Dutch–Belgian lung-cancer screening trial (Nederlands–Leuvens Longkanker Screenings Onderzoek) the effects of screening on lung-cancer mortality were consistently more favourable than in men.4de Koning HJ van der Aalst CM de Jong PA et al.Reduced lung-cancer mortality with volume CT screening in a randomized trial.N Engl J Med. 2020; 382: 503-513Crossref PubMed Scopus (1382) Google Scholar Data on people with lung cancer from the Cancer Registry of Norway also showed that men had an increased risk of excess death at 5 years compared with women irrespective of stage, age, length of time since diagnosis, and histological subgroup.5Sagerup CM Småstuen M Johannesen TB Helland Å Brustugun OT Sex-specific trends in lung cancer incidence and survival: a population study of 40 118 cases.Thorax. 2011; 66: 301-307Crossref PubMed Scopus (108) Google Scholar Ou and colleagues6Ou S-HI Ziogas A Zell JA Asian ethnicity is a favorable prognostic factor for overall survival in non-small cell lung cancer (NSCLC) and is independent of smoking status.J Thorac Oncol. 2009; 4: 1083-1093Summary Full Text Full Text PDF PubMed Scopus (103) Google Scholar showed that Asian ethnicity was an independent, favourable prognostic factor for overall survival in NSCLC regardless of smoking status. More work is needed to better understand the benefits of smoking cessation in these different subgroups, specifically why there are differences by sex and ethnicity. This is particularly important when considering adapting smoking-cessation interventions and messaging to different groups. Lung-cancer screening is a key strategy in reducing lung-cancer mortality through early diagnosis and effective treatment. Faers and colleagues3Fares AF Li Y Jiang M et al.Association between duration of smoking abstinence before non-small-cell lung cancer diagnosis and survival: a retrospective, pooled analysis of cohort studies.Lancet Public Health. 2023; 8: e691-e700Google Scholar interpret their findings in the context of lung-cancer screening programmes because mortality from NSCLC is reduced after 1 year of smoking cessation and show that overall survival is probably improved after smoking cessation if a lung cancer is detected at subsequent incident screening rounds. Findings from their study should therefore be used to instigate positive action from the commissioners of lung-cancer screening programmes as nations progress with consideration of and plans to implement lung-cancer screening programmes; decisions should be made on the delivery and funding for smoking-cessation interventions. Attendance at lung-cancer screening is a so-called teachable moment whereby people who smoke might be more receptive to an offer of support to stop smoking.7McBride CM Emmons KM Lipkus IM Understanding the potential of teachable moments: the case of smoking cessation.Health Educ Res. 2003; 18: 156-170Crossref PubMed Scopus (875) Google Scholar A 2023 systematic review showed that stop-smoking interventions delivered within lung-cancer screening settings are effective, with the strongest evidence for high-intensity intervention,8Williams PJ Philip KE Alghamdi SM et al.Strategies to deliver smoking cessation interventions during targeted lung health screening—a systematic review and meta-analysis.Chron Respir Dis. 2023; 20 (14799731231183446)Crossref Scopus (0) Google Scholar and modelling has shown that embedding stop-smoking support for individuals who smoke and attend lung-cancer screening can decrease deaths by 14% and increase overall life-years by 81%.9Cao P Jeon J Levy DT et al.Potential impact of cessation interventions at the point of lung cancer screening on lung cancer and overall mortality in the United States.J Thorac Oncol. 2020; 15: 1160-1169Summary Full Text Full Text PDF PubMed Scopus (36) Google Scholar These findings should also be incorporated into public health messaging, counteracting the often fatalistic views of smokers that the damage is already done and that there is no benefit to quitting smoking or attending lung-cancer screening.10Quaife SL Marlow LAV McEwen A Janes SM Wardle J Attitudes towards lung cancer screening in socioeconomically deprived and heavy smoking communities: informing screening communication.Health Expect. 2017; 20: 563-573Crossref PubMed Scopus (92) Google Scholar The message from the evidence is clear—no time is too late to quit smoking. RLM receives research funding from Yorkshire Cancer Research, Cancer Research UK, Horizon 2020, and the UK Prevention Research Partnership; receives speaker fees and travel reimbursement from Astra Zeneca; receives consultancy fees and is a trustee for Action on Smoking and Heath; and is a member of the Royal College of Physicians Tobacco Advisory Group. EO'D declares no competing interests. Association between duration of smoking abstinence before non-small-cell lung cancer diagnosis and survival: a retrospective, pooled analysis of cohort studiesIn this large, pooled analysis of cohort studies across Asia, Europe, North America, and South America, overall survival was improved in patients with NSCLC whose duration of smoking abstinence before diagnosis was as short as 1 year. These findings suggest that quitting smoking can improve overall survival, even if NSCLC is diagnosed at a later lung-cancer screening visit. These findings also support the implementation of public health smoking cessation strategies at any time. Full-Text PDF Open Access